Objective: To investigate whether children born to older mothers have an increased risk of type 1 diabetes by performing a meta-analysis using individual patient data to adjust for recognised confounders.

Research design and methods: Relevant studies published before June 2009 were identified from MEDLINE, Web of Science and EMBASE. Authors of studies were contacted and asked to provide individual patient data or conduct pre-specified analyses. Risk estimates of type 1 diabetes by category of maternal age were calculated for each included study, before and after adjustment for potential confounders. Meta-analysis techniques were used to derive combined odds ratios, and investigate heterogeneity between studies.

Results: Data were available for 5 cohort and 25 case-control studies, including 14,724 cases of type 1 diabetes. Overall, there was, on average, a 5% (95% CI 2%, 9%) increase in childhood type 1 diabetes odds per 5 year increase in maternal age (P=0.006), but there was heterogeneity between studies (heterogeneity I2= 70%). In studies with a low risk of bias there was a more marked increase in diabetes odds of 10% per 5 year increase in maternal age. Adjustments for potential confounders little altered these estimates.

Conclusions: There was evidence of a weak but significant linear increase in the risk of childhood type 1 diabetes across the range of maternal ages, but the magnitude of association varied between studies. A very small percentage of the increase in the incidence of childhood type 1 diabetes in recent years could be explained by increases in maternal age.


peer-reviewed, diabetes mellitus, type 1, epidemiology, maternal age



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